Requiem shark
Requiem sharks are sharks of the family Carcharhinidae in the order Carcharhiniformes, containing migratory, live-bearing sharks of warm seas (sometimes of brackish or fresh water) such as the spinner shark, the blacknose shark, the blacktip shark, the blacktail reef shark, and the blacktip reef shark. The name may be related to the French word for shark, requin, which is itself of disputed etymology. One derivation of the latter is from Latin requiem ("rest"), which would thereby create a cyclic etymology (requiem-requin-requiem), but other sources derive it from the verb reschignier ("to grimace while baring teeth"). Family members have the usual carcharhiniforme characteristics. Their eyes are round, and one or two gill slits fall over the pectoral fin base. Most species are viviparous, the young being born fully developed. They vary widely in size, from as small as 69 cm (2.26 ft) adult length in the Australian sharpnose shark, up to 5.5-7 m (18-23 ft) adult length in the tiger shark, the largest of the various species. Requiem sharks are responsible for a large proportion of attacks on humans; however, due to the difficulty in identifying individual species, a degree of inaccuracy exists in attack records. Classification The 60 species of requiem shark are grouped into 12 genera: * Genus Galeocerdo ** Galeocerdo cuvier (tiger shark) * Genus Scoliodon ** Scoliodon laticaudus (spadenose shark) ** Scoliodon macrorhynchos (Pacific spadenose shark) * Genus Carcharhinus ** Carcharhinus acronotus (blacknose shark) ** Carcharhinus albimarginatus (silvertip shark) ** Carcharhinus altimus (bignose shark) ** Carcharhinus amblyrhynchoides (graceful shark) ** Carcharhinus amblyrhynchos (grey reef shark) ** Carcharhinus amboinensis (pigeye shark) ** Carcharhinus borneensis (Borneo shark) ** Carcharhinus brachyurus (copper shark) ** Carcharhinus brevipinna (spinner shark) ** Carcharhinus cautus (nervous shark) ** Carcharhinus cerdale (Pacific smalltail shark) ** Carcharhinus coatesi (Coates' shark) ** Carcharhinus dussumieri (whitecheek shark) ** Carcharhinus falciformis (silky shark) ** Carcharhinus fitzroyensis (creek whaler) ** Carcharhinus galapagensis (Galapagos shark) ** Carcharhinus hemiodon (Pondicherry shark) ** Carcharhinus humani (Human's whaler shark) ** Carcharhinus isodon (finetooth shark) ** Carcharhinus leiodon (smoothtooth blacktip shark) ** Carcharhinus leucas (bull shark) ** Carcharhinus limbatus (blacktip shark) ** Carcharhinus longimanus (oceanic whitetip shark) ** Carcharhinus macloti (hardnose shark) ** Carcharhinus melanopterus (blacktip reef shark) ** Carcharhinus obscurus (dusky shark) ** Carcharhinus obsolerus (lost shark) ** Carcharhinus perezi (Caribbean reef shark) ** Carcharhinus plumbeus (sandbar shark) ** Carcharhinus porosus (smalltail shark) ** Carcharhinus sealei (blackspot shark) ** Carcharhinus signatus (night shark) ** Carcharhinus sorrah (spot-tail shark) ** Carcharhinus tilstoni (Australian blacktip shark) ** Carcharhinus tjutjot (Indonesian whaler shark) ** Carcharhinus sp. A not yet described (false smalltail shark) * Genus Glyphis ** Glyphis fowlerae (Borneo river shark) ** Glyphis gangeticus (Ganges shark) ** Glyphis garricki (northern river shark) ** Glyphis glyphis (speartooth shark) ** Glyphis siamensis (Irrawaddy river shark) ** Glyphis sp. Not yet described (Mukah river shark) * Genus Lamiopsis ** Lamiopsis temminckii (broadfin shark) ** Lamiopsis tephrodes (Borneo broadfin shark) * Genus Nasolamia ** Nasolamia velox (whitenose shark) * Genus Negaprion ** Negaprion acutidens (sicklefin lemon shark) ** Negaprion brevirostris (lemon shark) ** †''Negaprion eurybathrodon'' * Genus Prionace ** Prionace glauca (blue shark) * Genus Rhizoprionodon ** Rhizoprionodon acutus (milk shark) ** Rhizoprionodon lalandii (Brazilian sharpnose shark) ** Rhizoprionodon longurio (Pacific sharpnose shark) ** Rhizoprionodon oligolinx (grey sharpnose shark) ** Rhizoprionodon porosus (Caribbean sharpnose shark) ** Rhizoprionodon taylori (Australian sharpnose shark) ** Rhizoprionodon terraenovae (Atlantic sharpnose shark) * Genus Loxodon ** Loxodon macrorhinus (Sliteye shark) * Genus Isogomphodon ** Isogomphodon oxyrhynchus (daggernose shark) * Genus Triaenodon ** Triaenodon obesus (whitetip reef shark) Conservation Status Many species of requiem sharks are classified by the IUCN as being "Near Threatened" or "Vulnerable", with several being classified as "Endangered", or "Critically Endangered", such as the daggernose shark and all river sharks of the genus ''Glyphis ''due to limited distributions or heavy fishing pressures. Many, like the grey reef shark, tiger shark and sandbar shark are hunted for their meat and fins, while their skins have been used in leather in many areas. However, many species, such as tiger sharks, various requiem sharks such as the grey reef, blacktip reef, silvertip, and whitetip reef sharks are highly valued alive for the money they bring to local communities through ecotourism. This value is such that these sharks are often considered more valuable alive than dead in the local communities they may dwell near or around due to the added wealth and prosperity they bring. Many species of requiem sharks are also highly sought for public aquariums, as they are hardy and resilient animals. Some, such as the lemon, bull, grey and Caribbean reef sharks, blacktips and blacktip reef sharks, whitetip reef sharks, and tiger sharks are popular in the aquarium trade, and some small species may find their ways into large privately owned aquariums. Others, like the oceanic whitetip and blue shark, rarely are seen in aquaria due to the demands and difficulties in keeping oceanic shark species that have difficulties navigating the confines of tanks.Category:Chondrichthyes Category:Elasmobranchs Category:Sharks Category:Carcharhiniformes Category:Carcharhinidae